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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull futex fixes from Ingo Molnar:
- Enforce that the private futex owner shares the mm when attaching
(Kyle Zeng, Thomas Gleixner)
- Fix race on the initial mm->futex.phash.ref allocation (Hyunwoo Kim)
- Fix might_sleep() warning in futex_pivot_pending() (Peter Zijlstra)
* tag 'locking-urgent-2026-08-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
futex: Fix might_sleep() warning in futex_pivot_pending()
futex: Fix race on the initial mm->futex.phash.ref allocation
futex: Clean up the redundant exit/exec functions
futex/pi: Plug private futex exec() race
futex: Sanitize and document task_struct::futex::state transitions
futex/pi: Reject cross-mm private futex owners
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futex_exit_release() and futex_exec_release() are identical now. That means
also exit_mm_release() and exec_mm_release() are identical.
Consolidate the whole lot and remove the redundant copies.
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Kyle Zeng <kylebot@openai.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
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The check for private futexes whether the waiter's mm, which is stored in
the futex_key and copied into the pi_state, is the same as the owner's mm
is not sufficient for exec(). exec() has a gap where the mm check fails to
give the correct answer:
exec()
...
exec_release_mm()
futex_exec_release()
tsk::futex::exit_state = EXITING;
cleanup_robust_list();
1) tsk::futex::exit_state = OK;
...
old_mm = tsk::mm;
2) tsk::mm = ->mm;
Between #1 and #2 the check for the mm is wrong as that mm is about to be
swapped out and eventually freed.
Plug this gap by:
1) Setting tsk::futex::exit_state to FUTEX_STATE_DEAD in
futex_exec_release()
2) Setting tsk::futex::exit_state to FUTEX_STATE_OK after
the mm has been switched.
From a futex point of view the task is dead after it finished the robust
list cleanup up to the point where it sets the state to OK again.
Fixes: 80367ad01d93 ("futex: Add basic infrastructure for local task local hash")
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Kyle Zeng <kylebot@openai.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
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A 'B' entry's load program selects its interpreter by absolute path,
which open_exec() resolves at exec time in the mount namespace of whoever
runs the binary. The handler names an interpreter but does not get to say
which file that is. Whoever controls the filesystem view of the exec
decides that instead.
Static entries settled this long ago with 'F'. The interpreter is opened
at registration in the registrant's context and every exec runs a clone
of that file. Give a 'B' entry the same, for as many interpreters as it
needs.
An entry registered with 'D' cannot be matched yet, so it still belongs
to whoever is configuring it and can be given interpreters one write at a
time:
echo ':qemu:B::::qemu_user:D' > register
echo '+aarch64 /usr/bin/qemu-aarch64' > qemu
echo '+arm /usr/bin/qemu-arm' > qemu
echo 1 > qemu
Each path is opened by its write, with the credentials the entry file
was opened with, by the same helper that opens an 'F' interpreter. The
load program picks one per exec with bpf_binprm_select_interp() and the
entry hands out a clone of it. Nothing is resolved again, in any
namespace. The path is everything past the first space, so no
interpreter has to fit in a register string. An entry binds at most a
hundred interpreters (BINFMT_MISC_INTERP_MAX). Every binding pins a
struct file that no file descriptor accounts for, so RLIMIT_NOFILE does
not apply and some cap is needed. A hundred is plenty and raising it
later is cheap, lowering it is not.
Selection is by name so the register string and the program need not
agree on an order, and so the handler is not tied to where a distribution
puts its interpreters. A name is a single word of printable ASCII so the
entry file can report 'name path' lines. The interpreter runs under the
path it was registered under.
The entry file reads user memory once. bm_entry_write() copies the write
in and dispatches on the first byte, and parse_command() takes the copied
buffer. The status file has no binding to spell, so it keeps its own
small copy in read_command().
That moves the length cap ahead of the dispatch. A write to an entry file
longer than a binding can be is now refused with -E2BIG, and one from a
bad address reports -EFAULT, where the command parser used to report
-EINVAL for anything past three bytes.
Configurations of one instance are kept apart by the lock removal
already takes. Reading the set out of the entry file takes no lock.
Bindings are rcu-published and the open entry file pins the entry
together with everything it bound, so a reader either sees a whole node
or misses it. The interpreter is opened before the configuration lock
because resolving the path may walk this very filesystem, and only
after the command has been parsed and the name validated from the
copied buffer, so a write that can never bind opens nothing and the
errno reflects the actual failure.
Link: https://patch.msgid.link/20260730-work-binfmt_misc-preopen-v1-7-4a0b0da71f16@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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binfmt_misc currently supports an execution model where the registered
interpreter becomes the executed program and the matched binary is
handed to it as payload. The upcoming binfmt_misc loader mode inverts
this. The matched binary remains the executed program and the registered
interpreter is substituted into the role the binary's PT_INTERP would
have played.
Add the channel for that hand-over. bprm->loader carries an
open_exec-style struct file reference from the binfmt_misc match to the
binary format that consumes it. Unlike bprm->interpreter it does not
request a restart of the format search. The stashing handler declines
the exec with -ENOEXEC and the search continues to the real format in
the same round.
Both ELF loaders consume it, so give them the two helpers to do it with
rather than a copy each. bprm_open_interpreter() hands out the substitute
in place of what PT_INTERP names and bprm_drop_loader() releases one that
turned out not to apply.
Establish the complete lifecycle up front so a stashed loader can
neither leak nor be silently ignored.
- Chain restart: if another format wins the round by staging
bprm->interpreter (binfmt_script) the stashed loader belonged to
the file being replaced. Drop it at the top of the swap block in
exec_binprm().
- Unclaimed or error: free_bprm() releases a still-stashed loader
next to the other bprm file references.
- Silent non-substitution: a final format that reaches
begin_new_exec() with a pending loader would run the binary while
ignoring the override. Refuse with -ENOEXEC before the point of no
return. Formats that do not know about the override (binfmt_flat,
out-of-tree) need no changes.
Link: https://patch.msgid.link/20260721-work-bpf-binfmt_misc-ptinterp-v2-15-e57866e4ae0f@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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When binfmt_misc dispatches a binary to an interpreter, the interpreter
becomes bprm->file and begin_new_exec() labels mm->exe_file with it. For
wine or qemu-user that is the point. For the transparent mode it
defeats the point. The interpreter is an implementation detail and the
process's identity is the binary. Relocatable programs that locate
themselves via /proc/self/exe find the dynamic linker instead [1].
Userspace cannot get this right on its own. PR_SET_MM_MAP's exe_fd is
gated on checkpoint_restore_ns_capable() in the caller's own user
namespace - that is how CRIU restores an exe link - so the ability to
retarget mm->exe_file is not what this adds. What userspace cannot do
is have the link be right from the first instruction. Credentials are
unaffected either way: they still derive from the interpreter unless
'C' says otherwise.
bprm->executable is the file execve() access-checked and kept open for
AT_EXECFD. It is already the file would_dump() bases the dumpability
decision on and the file bprm->execfd_creds derives credentials from.
Label mm->exe_file with it when the dispatch is transparent and the
identity is correct from the start. The label names precisely the file
the caller passed to execve().
Write-denial moves along with the label. Rather than tracking per mode
who still owes a release, the denial do_open_execat() took stays on
bprm->executable until the file is handed over. begin_new_exec() drops
it right before installing the descriptor - set_mm_exe_file() has taken
its own denial on the identity file by then - and free_bprm() releases
an unconsumed executable with do_close_execat() like the other exec
files. For a transparent dispatch the result is exact parity with a
direct execution: a concurrently written binary fails execve() with
-ETXTBSY at open and a running one cannot be opened for writing. The
interpreter consequently is not exe-pinned and matches the role it has
in a native PT_INTERP exec. A classic execfd dispatch now keeps the
binary write-denied until the exec completes rather than only until the
interpreter swap; the difference is confined to the exec itself.
Nothing sets BINPRM_FLAGS_TRANSPARENT_INTERP yet; the transparent
dispatch machinery in binfmt_misc follows and raises it from birth, so
the label and the aux vector bit that announces it appear together.
Link: https://inbox.sourceware.org/libc-alpha/87ik6fymha.fsf@oldenburg.str.redhat.com [1]
Link: https://patch.msgid.link/20260721-work-bpf-binfmt_misc-ptinterp-v2-9-e57866e4ae0f@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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When the format search stages an interpreter exec_binprm() swaps it
in and releases the file it replaces. Dropping the write denial the
open took is done manually ahead of both release paths. The one path
that keeps the file silently relies on it not being called.
Let's just use do_close_execat() on the two paths that release the file
and drop the denial explicitly on the one that does not.
No functional change.
Link: https://patch.msgid.link/20260721-work-bpf-binfmt_misc-ptinterp-v2-6-e57866e4ae0f@kernel.org
Reviewed-by: Farid Zakaria <farid.m.zakaria@gmail.com>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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The upcoming bpf-backed binfmt_misc handlers decide how a binary is run
programmatically at exec time: the interpreter itself, an optional
single argument to pass to it, and the invocation flags that a static
binfmt_misc entry fixes at registration time. The selection runs before
load_misc_binary() has copied the binary path from bprm->interp into
the argument vector, so the selecting program cannot go through
bprm_change_interp() directly without clobbering argv[1].
Stage the selected state in the bprm instead, grouped in struct
binfmt_misc_bpf and embedded anonymously in struct linux_binprm so the
bprm->bpf_* accesses stay direct. The bprm is exclusively owned by the
task doing the exec so no synchronization is needed. The consumers
free and clear the fields once the exec attempt that set them is
finished; free_bprm() covers all error paths.
Link: https://patch.msgid.link/20260714-work-bpf-binfmt_misc-v2-1-57b7529c002c@kernel.org
Reviewed-by: Farid Zakaria <farid.m.zakaria@gmail.com>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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The stop value is derived from bprm->p >> PAGE_SHIFT. The index variable
is an unsigned long. If bprm->p drops below PAGE_SIZE and stop becomes
zero the loop condition index >= stop is always true.
After the index == 0 iteration the decrement wraps to ULONG_MAX and
bprm->page[ULONG_MAX] reads sizeof(void *) bytes in front of the array.
The pointer has wrapped to -1. That garbage pointer is then passed to
kmap_local_page() and PAGE_SIZE bytes are copied from wherever that
lands into the stack of the process being created. And the loop doesn't
terminate either...
Getting there only requires bprm->p < PAGE_SIZE. On !MMU
bprm_set_stack_limit() and bprm_hit_stack_limit() are empty. So the only
constraint on how far bprm->p is pushed down is valid_arg_len(), i.e.
that each individual string still fits in what is left.
bprm->p starts at PAGE_SIZE * MAX_ARG_PAGES - sizeof(void *) so a
single argument or environment string of a little over 31 pages leaves
it in the first page:
Oops - load access fault [#1]
CPU: 0 UID: 0 PID: 1 Comm: victim Not tainted 7.2.0-rc4 #1
epc : __memcpy+0xd4/0xf8
ra : transfer_args_to_stack+0xaa/0xae
s4 : ffffffffffffffff s2 : 0000000000000000
a1 : ffffffdc98000000 a2 : 0000000000001000
status: 0000000a00001880 badaddr: ffffffdc98000000 cause: 0000000000000005
[<801a5324>] __memcpy+0xd4/0xf8
[<800d5f6a>] load_flat_binary+0x43a/0x65e
[<800a2de4>] bprm_execve+0x1d4/0x316
[<800a351a>] do_execveat_common+0x12e/0x138
[<800a3d44>] __riscv_sys_execve+0x38/0x4e
Kernel panic - not syncing: Fatal exception in interrupt
This is an arcane bug but we should still fix it.
Count down from MAX_ARG_PAGES so the loop ends when index reaches stop,
stop == 0 included. The iterations performed are unchanged for every
other value of stop.
Only CONFIG_MMU=n builds are affected, transfer_args_to_stack() is used
by binfmt_flat and binfmt_elf_fdpic on nommu only.
The loop predates git history. commit 7e7ec6a93434
("elf_fdpic_transfer_args_to_stack(): make it generic") only moved it
from binfmt_elf_fdpic.c into fs/exec.c and narrowed the copy to the used
part of the first page. The condition and the decrement are unchanged
from 2.6.12-rc2.
Link: https://patch.msgid.link/20260721-hochachtung-staumauer-pigmente-15d71f7d7d04@brauner
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Reviewed-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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The loop in exec_binprm() permits depth values 0 through 5, up to 5
successive binfmt rewrites (setting bprm->interpreter) until the 6th
one would fail on depth > 5 and return -ELOOP. The comment claimed 4
levels, which was wrong. Adjusting the code to allow only 4 rewrites
would be breaking userland, so fix the comment and not the code.
Reproducer (a chain of shebanged scripts followed by an ELF binary):
#!/bin/sh
tmp=$(mktemp -d)
echo $tmp
cd $tmp
mk () { echo $2 > $1; chmod +x $1; }
for i in $(seq 4); do
mk $i "#!$((i + 1))"
done
mk 5 '#!/bin/true'
./1 &&
echo '5 binfmt rewrites OK (1 -> 2 -> 3 -> 4 -> 5 -> /bin/true)'
mk 5 '#!6'
mk 6 '#!/bin/true'
./1 ||
echo '6 binfmt rewrites KO (1 -> 2 -> 3 -> 4 -> 5 -> 6 -> /bin/true)'
Signed-off-by: Alan Urmancheev <alan.urman@gmail.com>
Link: https://patch.msgid.link/20260623052322.74711-1-alan.urman@gmail.com
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull misc vfs updates from Christian Brauner:
"Features:
- Reduce pipe->mutex contention by pre-allocating pages outside the
lock in anon_pipe_write().
anon_pipe_write() called alloc_page() once per page while holding
pipe->mutex. The allocation can sleep doing direct reclaim and runs
memcg charging, which extends the critical section and stalls any
concurrent reader on the same mutex. Now up to 8 pages are
pre-allocated before the mutex is taken, leftovers are recycled
into the per-pipe tmp_page[] cache before unlock, and any remainder
is released after unlock, keeping the allocator out of the critical
section on both sides. On a writers x readers sweep with 64KB
writes against a 1 MB pipe throughput improves 6-28% and average
write latency drops 5-22%; under memory pressure - when the cost of
holding the mutex across reclaim is highest - throughput improves
21-48% and latency drops 17-33%. The microbenchmark is added to
selftests.
- uaccess/sockptr: fix the ignored_trailing logic in
copy_struct_to_user() to behave as documented and the usize check
in copy_struct_from_sockptr() for user pointers, and add
copy_struct_{from,to}_bounce_buffer() and copy_struct_to_sockptr()
helpers for upcoming users (IPPROTO_SMBDIRECT, IPPROTO_QUIC).
- bpf: add a sleepable bpf_real_inode() kfunc that resolves the real
inode backing a dentry via d_real_inode(). On overlayfs the inode
attached to the dentry doesn't carry the underlying device
information; this is used by the filesystem restriction BPF program
that was merged into systemd.
- docs: add guidelines for submitting new filesystems, motivated by
the maintenance burden abandoned and untestable filesystems impose
on VFS developers, blocking infrastructure work like folio
conversions and iomap migration.
Fixes:
- libfs: set SB_I_NOEXEC and SB_I_NODEV by default in init_pseudo()
and drop the now-redundant assignments in callers. This began as a
one-line dma-buf fix for a path_noexec() warning; a pseudo
filesystem has no reason not to set SB_I_NOEXEC. All init_pseudo()
callers were audited: the only visible effect is on dma-buf where
SB_I_NOEXEC silences the warning.
- Handle set_blocksize() failures in legacy filesystems (bfs, hpfs,
qnx4, jfs, befs, affs, isofs, minix, ntfs3, omfs). Mounting a
device with a sector size > PAGE_SIZE crashed roughly half of them;
the rest had the same missing error handling pattern. Plus a
follow-up releasing the superblock buffer_head when setting the
minix v3 block size fails.
- mount: honour SB_NOUSER in the new mount API.
- fs/fcntl: fix a SOFTIRQ-unsafe lock order in fasync signaling by
switching the process-group paths of send_sigio() and send_sigurg()
from read_lock(&tasklist_lock) to RCU, matching the single-PID
path.
- vfs: add an FS_USERNS_DELEGATABLE flag and set it for NFS, fixing
delegated NFS mounts (fsopen() in a container with the mount
performed by a privileged daemon) that broke when non-init
s_user_ns was tied to FS_USERNS_MOUNT.
- selftests/namespaces: fix a hang in nsid_test where an unreaped
grandchild kept the TAP pipe write-end open, a waitpid(-1) race in
listns_efault_test, and a false FAIL on kernels without listns()
where the tests should SKIP.
- filelock: fix the break_lease() stub signature for
CONFIG_FILE_LOCKING=n.
- init/initramfs_test: wait for the async initramfs unpacking before
running; the test and do_populate_rootfs() share the parser state.
- fs/coredump: reduce redundant log noise in
validate_coredump_safety().
- iomap: pass the correct length to fserror_report_io() in
__iomap_write_begin().
- backing-file: fix the backing_file_open() kerneldoc.
Cleanups:
- initramfs: refactor the cpio hex header parsing to use hex2bin()
instead of the hand-rolled simple_strntoul() which is reverted, and
extend the initramfs KUnit tests to cover header fields with 0x
prefixes.
- Replace __get_free_pages() and friends with kmalloc()/kzalloc()
across quota, proc, ocfs2/dlm, nilfs2, nfs, nfsd, libfs, jfs, jbd2,
isofs, fuse, select, namespace, configfs, binfmt_misc, bfs, and the
do_mounts init code - part of the larger work of replacing page
allocator calls with kmalloc().
- Use clear_and_wake_up_bit() in unlock_buffer() and
journal_end_buffer_io_sync() instead of open-coding the sequence.
- Drop unused VFS exports: unexport drop_super_exclusive(), remove
start_removing_user_path_at(), and fold __start_removing_path()
into start_removing_path().
- fs/read_write: narrow the __kernel_write() export with
EXPORT_SYMBOL_FOR_MODULES().
- vfs: uapi: retire octal and hex constants in favor of (1 << n) for
the O_ flags. Finding a free bit for a new flag across the
architectures was needlessly hard with the mixed bases.
- dcache: add extra sanity checks of dead dentries in dentry_free()
via a new DENTRY_WARN_ONCE() that also prints d_flags.
- iov_iter: use kmemdup_array() in dup_iter() to harden the
allocation against multiplication overflow.
- fs/pipe: write to ->poll_usage only once.
- vfs: remove an always-taken if-branch in find_next_fd().
- dcache: use kmalloc_flex() for struct external_name in __d_alloc().
- namei: use QSTR() instead of QSTR_INIT() in path_pts().
- sync_file_range: delete dead S_ISLNK code.
- Comment fixes: retire a stale comment in fget_task_next() and fix
assorted spelling mistakes"
* tag 'vfs-7.2-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (73 commits)
backing-file: fix backing_file_open() kerneldoc parameter
iomap: pass the correct len to fserror_report_io in __iomap_write_begin
vfs: add FS_USERNS_DELEGATABLE flag and set it for NFS
filelock: fix break_lease() stub signature for CONFIG_FILE_LOCKING=n
vfs: uapi: retire octal and hex numbers in favor of (1 << n) for O_ flags
bpf: add bpf_real_inode() kfunc
fs/read_write: Do not export __kernel_write() to the entire world
libfs: drop redundant SB_I_NOEXEC/SB_I_NODEV in init_pseudo() callers
libfs: set SB_I_NOEXEC and SB_I_NODEV by default in init_pseudo()
mount: honour SB_NOUSER in the new mount API
fs/fcntl: fix SOFTIRQ-unsafe lock order in fasync signaling
selftests/pipe: add pipe_bench microbenchmark
fs/pipe: pre-allocate pages outside pipe->mutex in anon_pipe_write
fs: retire stale comment in fget_task_next()
fs: fix spelling mistakes in comment
bfs: replace get_zeroed_page() with kzalloc()
binfmt_misc: replace __get_free_page() with kmalloc()
configfs: replace __get_free_pages() with kzalloc()
fs/namespace: use __getname() to allocate mntpath buffer
fs/select: replace __get_free_page() with kmalloc()
...
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exec_mmap() installs the new mm and then tears the old one down while
still holding exec_update_lock for writing -- and with cred_guard_mutex
held all the way to setup_new_exec():
setmax_mm_hiwater_rss(&tsk->signal->maxrss, old_mm);
mm_update_next_owner(old_mm);
mmput(old_mm);
Neither lock is needed for this. exec_update_lock only exists to make the
mm swap atomic with the later commit_creds(), so that permission-checking
readers (proc, ptrace, the futex robust list, perf, kcmp, mm_access())
never observe the new mm together with the old credentials. Those readers
all operate on task->mm, i.e. the new mm after the swap; none looks at the
detached old mm, its ->owner or signal->maxrss. cred_guard_mutex guards
credential calculation and is equally irrelevant here.
The cost is real: __mmput() runs exit_mmap() over the entire old address
space and can block in exit_aio() waiting for in-flight AIO, all while
holding exec_update_lock for writing and cred_guard_mutex. For execve() of
a large process this blocks ptrace_attach() and every exec_update_lock
reader for the duration of the teardown.
Stash the old mm in bprm->old_mm and release it from setup_new_exec()
after both locks are dropped. setup_new_exec() still runs before
setup_arg_pages() and the segment mappings, so the old address space is
freed before the new one is populated and peak memory is unchanged. The
ordering constraints are kept: old_mm's mmap_lock is still dropped in
exec_mmap() before mm_update_next_owner() (required since commit
31a78f23bac0 ("mm owner: fix race between swapoff and exit")), and
mm_update_next_owner() still precedes mmput(); both run in the execing
task's context, as mm_update_next_owner() requires.
If exec swaps the mm but fails before setup_new_exec() runs the old mm
would leak, so add a backstop in free_bprm(). The lazy-tlb case
(old_mm == NULL, e.g. kernel_execve()) has no address space to
free and is left in exec_mmap().
Link: https://patch.msgid.link/20260522-work-exit_mm-v1-1-bd32d5a560bb@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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The dumpable flag captured at execve() is consulted by
__ptrace_may_access() and several /proc owner / visibility checks.
It lives on mm_struct today, which exit_mm() clears from the task
long before the task itself is reaped.
exec_state is anchored to the execve() that established the current
privilege domain. CLONE_VM siblings refcount-share the parent's
exec_state via copy_exec_state(); non-CLONE_VM clones allocate a
fresh exec_state inheriting the parent's dumpable mode and user_ns
reference via task_exec_state_copy(). execve() allocates a fresh
instance (via alloc_task_exec_state() in begin_new_exec()) and
installs it under task_lock + exec_update_lock with
task_exec_state_replace(). init_task uses a static instance.
The dumpable mode now lives on task->exec_state->dumpable.
task->mm->flags no longer carries dumpability; MMF_DUMPABLE_MASK is
removed, but MMF_DUMPABLE_BITS is reserved so MMF_DUMP_FILTER_* bit
positions remain stable for the /proc/<pid>/coredump_filter ABI. The
task->user_dumpable cache bit and its assignment in exit_mm() are
removed; readers go through get_dumpable(task) directly.
coredump_params gains a snapshot field cprm.dumpable, populated from
get_dumpable(current) at vfs_coredump() entry, replacing the previous
__get_dumpable(cprm->mm_flags) consumers in fs/coredump.c and
fs/pidfs.c.
The user namespace recorded at execve() is consulted by
__ptrace_may_access() and by /proc/PID/* owner derivation. Move the
captured user_ns onto task_exec_state, which stays attached to the task
past exit_mm() and across exit_files().
bprm grows a user_ns field staged in bprm_mm_init() with the caller's
user_ns, narrowed by would_dump() to the closest privileged ancestor,
and consumed by exec_mmap() via alloc_task_exec_state(bprm->user_ns).
free_bprm() releases the staging reference.
mm_struct loses ->user_ns entirely. Initializers in init-mm, efi_mm,
and the implicit one in mm_init()/dup_mm()/mm_alloc() are removed;
__mmdrop() drops the matching put_user_ns(). The kthread_use_mm()
WARN_ON_ONCE(!mm->user_ns) is no longer meaningful and goes too.
Reviewed-by: Jann Horn <jannh@google.com>
Link: https://patch.msgid.link/20260520-work-task_exec_state-v3-4-69f895bc1385@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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Replace the SUID_DUMP_DISABLE/USER/ROOT preprocessor constants with
enum task_dumpable. Numeric values are preserved (kernel.suid_dumpable
sysctl and prctl(PR_SET_DUMPABLE) ABI), so this is a pure rename with
no behavioral change.
Subsequent commits relocate dumpability onto a per-task structure
where the enum type will allow stronger type-checking on the new API.
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: David Hildenbrand (arm) <david@kernel.org>
Link: https://patch.msgid.link/20260520-work-task_exec_state-v3-1-69f895bc1385@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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Currently, writing to 'core_pattern' or 'suid_dumpable' sysctl nodes
always triggers validate_coredump_safety(), even if the values have
not changed. This results in redundant warning messages in dmesg:
"Unsafe core_pattern used with fs.suid_dumpable=2..."
This patch optimizes the procfs handlers to only invoke the safety
validation when an actual change in the configuration is detected:
1. In proc_dostring_coredump(), compare the new core_pattern string
with the existing one using strncmp().
2. In proc_dointvec_minmax_coredump(), check if the new suid_dumpable
value differs from the previous one.
This keeps the kernel log clean from repetitive warnings when
re-applying the same sysctl settings.
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Link: https://patch.msgid.link/20260410080918.2319-1-lirongqing@baidu.com
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
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Use strnlen() to limit source string scanning to 'TASK_COMM_LEN - 1'
bytes.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20260401152039.724811-3-thorsten.blum@linux.dev
Signed-off-by: Kees Cook <kees@kernel.org>
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This was done entirely with mindless brute force, using
git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'
to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.
Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.
For the same reason the 'flex' versions will be done as a separate
conversion.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:
Single allocations: kmalloc(sizeof(TYPE), ...)
are replaced with: kmalloc_obj(TYPE, ...)
Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with: kmalloc_objs(TYPE, COUNT, ...)
Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...)
(where TYPE may also be *VAR)
The resulting allocations no longer return "void *", instead returning
"TYPE *".
Signed-off-by: Kees Cook <kees@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs 'struct filename' updates from Al Viro:
"[Mostly] sanitize struct filename handling"
* tag 'pull-filename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (68 commits)
sysfs(2): fs_index() argument is _not_ a pathname
alpha: switch osf_mount() to strndup_user()
ksmbd: use CLASS(filename_kernel)
mqueue: switch to CLASS(filename)
user_statfs(): switch to CLASS(filename)
statx: switch to CLASS(filename_maybe_null)
quotactl_block(): switch to CLASS(filename)
chroot(2): switch to CLASS(filename)
move_mount(2): switch to CLASS(filename_maybe_null)
namei.c: switch user pathname imports to CLASS(filename{,_flags})
namei.c: convert getname_kernel() callers to CLASS(filename_kernel)
do_f{chmod,chown,access}at(): use CLASS(filename_uflags)
do_readlinkat(): switch to CLASS(filename_flags)
do_sys_truncate(): switch to CLASS(filename)
do_utimes_path(): switch to CLASS(filename_uflags)
chdir(2): unspaghettify a bit...
do_fchownat(): unspaghettify a bit...
fspick(2): use CLASS(filename_flags)
name_to_handle_at(): use CLASS(filename_uflags)
vfs_open_tree(): use CLASS(filename_uflags)
...
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do_file_open() doesn't.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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All linux_binprm instances come from alloc_bprm() and are unconditionally
destroyed by free_bprm() in the end of the same scope. IOW, CLASS()
machinery is a decent fit for those.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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... and convert its callers to CLASS(filename...)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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All of them are wrappers for do_execveat_common() and each has
exactly one caller. The only difference is in the way they are
constructing argv/envp arguments for do_execveat_common() and
that's easy to do with less boilerplate.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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alloc_bprm() starts with do_open_execat() and it will do the right
thing if given ERR_PTR() for name. Allows to drop such checks in
its callers...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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"filp" thing never made sense; seeing that there are exactly 4 callers
in the entire tree (and it's neither exported nor even declared in
linux/*/*.h), there's no point keeping that ugliness.
FWIW, the 'filp' thing did originate in OSD&I; for some reason Tanenbaum
decided to call the object representing an opened file 'struct filp',
the last letter standing for 'position'. In all Unices, Linux included,
the corresponding object had always been 'struct file'...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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min_t(unsigned int, a, b) casts an 'unsigned long' to 'unsigned int'.
Use min(a, b) instead as it promotes any 'unsigned int' to 'unsigned long'
and so cannot discard significant bits.
A couple of places need umin() because of loops like:
nfolios = DIV_ROUND_UP(ret + start, PAGE_SIZE);
for (i = 0; i < nfolios; i++) {
struct folio *folio = page_folio(pages[i]);
...
unsigned int len = umin(ret, PAGE_SIZE - start);
...
ret -= len;
...
}
where the compiler doesn't track things well enough to know that
'ret' is never negative.
The alternate loop:
for (i = 0; ret > 0; i++) {
struct folio *folio = page_folio(pages[i]);
...
unsigned int len = min(ret, PAGE_SIZE - start);
...
ret -= len;
...
}
would be equivalent and doesn't need 'nfolios'.
Most of the 'unsigned long' actually come from PAGE_SIZE.
Detected by an extra check added to min_t().
Signed-off-by: David Laight <david.laight.linux@gmail.com>
Link: https://patch.msgid.link/20251119224140.8616-31-david.laight.linux@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull rseq updates from Thomas Gleixner:
"A large overhaul of the restartable sequences and CID management:
The recent enablement of RSEQ in glibc resulted in regressions which
are caused by the related overhead. It turned out that the decision to
invoke the exit to user work was not really a decision. More or less
each context switch caused that. There is a long list of small issues
which sums up nicely and results in a 3-4% regression in I/O
benchmarks.
The other detail which caused issues due to extra work in context
switch and task migration is the CID (memory context ID) management.
It also requires to use a task work to consolidate the CID space,
which is executed in the context of an arbitrary task and results in
sporadic uncontrolled exit latencies.
The rewrite addresses this by:
- Removing deprecated and long unsupported functionality
- Moving the related data into dedicated data structures which are
optimized for fast path processing.
- Caching values so actual decisions can be made
- Replacing the current implementation with a optimized inlined
variant.
- Separating fast and slow path for architectures which use the
generic entry code, so that only fault and error handling goes into
the TIF_NOTIFY_RESUME handler.
- Rewriting the CID management so that it becomes mostly invisible in
the context switch path. That moves the work of switching modes
into the fork/exit path, which is a reasonable tradeoff. That work
is only required when a process creates more threads than the
cpuset it is allowed to run on or when enough threads exit after
that. An artificial thread pool benchmarks which triggers this did
not degrade, it actually improved significantly.
The main effect in migration heavy scenarios is that runqueue lock
held time and therefore contention goes down significantly"
* tag 'core-rseq-2025-11-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (54 commits)
sched/mmcid: Switch over to the new mechanism
sched/mmcid: Implement deferred mode change
irqwork: Move data struct to a types header
sched/mmcid: Provide CID ownership mode fixup functions
sched/mmcid: Provide new scheduler CID mechanism
sched/mmcid: Introduce per task/CPU ownership infrastructure
sched/mmcid: Serialize sched_mm_cid_fork()/exit() with a mutex
sched/mmcid: Provide precomputed maximal value
sched/mmcid: Move initialization out of line
signal: Move MMCID exit out of sighand lock
sched/mmcid: Convert mm CID mask to a bitmap
cpumask: Cache num_possible_cpus()
sched/mmcid: Use cpumask_weighted_or()
cpumask: Introduce cpumask_weighted_or()
sched/mmcid: Prevent pointless work in mm_update_cpus_allowed()
sched/mmcid: Move scheduler code out of global header
sched: Fixup whitespace damage
sched/mmcid: Cacheline align MM CID storage
sched/mmcid: Use proper data structures
sched/mmcid: Revert the complex CID management
...
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull fd prepare updates from Christian Brauner:
"This adds the FD_ADD() and FD_PREPARE() primitive. They simplify the
common pattern of get_unused_fd_flags() + create file + fd_install()
that is used extensively throughout the kernel and currently requires
cumbersome cleanup paths.
FD_ADD() - For simple cases where a file is installed immediately:
fd = FD_ADD(O_CLOEXEC, vfio_device_open_file(device));
if (fd < 0)
vfio_device_put_registration(device);
return fd;
FD_PREPARE() - For cases requiring access to the fd or file, or
additional work before publishing:
FD_PREPARE(fdf, O_CLOEXEC, sync_file->file);
if (fdf.err) {
fput(sync_file->file);
return fdf.err;
}
data.fence = fd_prepare_fd(fdf);
if (copy_to_user((void __user *)arg, &data, sizeof(data)))
return -EFAULT;
return fd_publish(fdf);
The primitives are centered around struct fd_prepare. FD_PREPARE()
encapsulates all allocation and cleanup logic and must be followed by
a call to fd_publish() which associates the fd with the file and
installs it into the caller's fdtable. If fd_publish() isn't called,
both are deallocated automatically. FD_ADD() is a shorthand that does
fd_publish() immediately and never exposes the struct to the caller.
I've implemented this in a way that it's compatible with the cleanup
infrastructure while also being usable separately. IOW, it's centered
around struct fd_prepare which is aliased to class_fd_prepare_t and so
we can make use of all the basica guard infrastructure"
* tag 'vfs-6.19-rc1.fd_prepare.fs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (42 commits)
io_uring: convert io_create_mock_file() to FD_PREPARE()
file: convert replace_fd() to FD_PREPARE()
vfio: convert vfio_group_ioctl_get_device_fd() to FD_ADD()
tty: convert ptm_open_peer() to FD_ADD()
ntsync: convert ntsync_obj_get_fd() to FD_PREPARE()
media: convert media_request_alloc() to FD_PREPARE()
hv: convert mshv_ioctl_create_partition() to FD_ADD()
gpio: convert linehandle_create() to FD_PREPARE()
pseries: port papr_rtas_setup_file_interface() to FD_ADD()
pseries: convert papr_platform_dump_create_handle() to FD_ADD()
spufs: convert spufs_gang_open() to FD_PREPARE()
papr-hvpipe: convert papr_hvpipe_dev_create_handle() to FD_PREPARE()
spufs: convert spufs_context_open() to FD_PREPARE()
net/socket: convert __sys_accept4_file() to FD_ADD()
net/socket: convert sock_map_fd() to FD_ADD()
net/kcm: convert kcm_ioctl() to FD_PREPARE()
net/handshake: convert handshake_nl_accept_doit() to FD_PREPARE()
secretmem: convert memfd_secret() to FD_ADD()
memfd: convert memfd_create() to FD_ADD()
bpf: convert bpf_token_create() to FD_PREPARE()
...
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Link: https://patch.msgid.link/20251123-work-fd-prepare-v4-21-b6efa1706cfd@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
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After removing the various condition bits earlier it turns out that one
extra information is needed to avoid setting event::sched_switch and
TIF_NOTIFY_RESUME unconditionally on every context switch.
The update of the RSEQ user space memory is only required, when either
the task was interrupted in user space and schedules
or
the CPU or MM CID changes in schedule() independent of the entry mode
Right now only the interrupt from user information is available.
Add an event flag, which is set when the CPU or MM CID or both change.
Evaluate this event in the scheduler to decide whether the sched_switch
event and the TIF bit need to be set.
It's an extra conditional in context_switch(), but the downside of
unconditionally handling RSEQ after a context switch to user is way more
significant. The utilized boolean logic minimizes this to a single
conditional branch.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20251027084307.578058898@linutronix.de
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Since commit 0190e4198e47 ("rseq: Deprecate RSEQ_CS_FLAG_NO_RESTART_ON_*
flags") the bits in task::rseq_event_mask are meaningless and just extra
work in terms of setting them individually.
Aside of that the only relevant point where an event has to be raised is
context switch. Neither the CPU nor MM CID can change without going through
a context switch.
Collapse them all into a single boolean which simplifies the code a lot and
remove the pointless invocations which have been sprinkled all over the
place for no value.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20251027084306.336978188@linutronix.de
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In be1e0283021e ("coredump: don't pointlessly check and spew warnings")
we tried to fix input validation so it only happens during a write to
core_pattern. This would avoid needlessly logging a lot of warnings
during a read operation. However the logic accidently got inverted in
this commit. Fix it so the input validation only happens on write and is
skipped on read.
Fixes: be1e0283021e ("coredump: don't pointlessly check and spew warnings")
Fixes: 16195d2c7dd2 ("coredump: validate socket name as it is written")
Reviewed-by: Jan Kara <jack@suse.cz>
Reported-by: Yu Watanabe <watanabe.yu@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- "mm, swap: improve cluster scan strategy" from Kairui Song improves
performance and reduces the failure rate of swap cluster allocation
- "support large align and nid in Rust allocators" from Vitaly Wool
permits Rust allocators to set NUMA node and large alignment when
perforning slub and vmalloc reallocs
- "mm/damon/vaddr: support stat-purpose DAMOS" from Yueyang Pan extend
DAMOS_STAT's handling of the DAMON operations sets for virtual
address spaces for ops-level DAMOS filters
- "execute PROCMAP_QUERY ioctl under per-vma lock" from Suren
Baghdasaryan reduces mmap_lock contention during reads of
/proc/pid/maps
- "mm/mincore: minor clean up for swap cache checking" from Kairui Song
performs some cleanup in the swap code
- "mm: vm_normal_page*() improvements" from David Hildenbrand provides
code cleanup in the pagemap code
- "add persistent huge zero folio support" from Pankaj Raghav provides
a block layer speedup by optionalls making the
huge_zero_pagepersistent, instead of releasing it when its refcount
falls to zero
- "kho: fixes and cleanups" from Mike Rapoport adds a few touchups to
the recently added Kexec Handover feature
- "mm: make mm->flags a bitmap and 64-bit on all arches" from Lorenzo
Stoakes turns mm_struct.flags into a bitmap. To end the constant
struggle with space shortage on 32-bit conflicting with 64-bit's
needs
- "mm/swapfile.c and swap.h cleanup" from Chris Li cleans up some swap
code
- "selftests/mm: Fix false positives and skip unsupported tests" from
Donet Tom fixes a few things in our selftests code
- "prctl: extend PR_SET_THP_DISABLE to only provide THPs when advised"
from David Hildenbrand "allows individual processes to opt-out of
THP=always into THP=madvise, without affecting other workloads on the
system".
It's a long story - the [1/N] changelog spells out the considerations
- "Add and use memdesc_flags_t" from Matthew Wilcox gets us started on
the memdesc project. Please see
https://kernelnewbies.org/MatthewWilcox/Memdescs and
https://blogs.oracle.com/linux/post/introducing-memdesc
- "Tiny optimization for large read operations" from Chi Zhiling
improves the efficiency of the pagecache read path
- "Better split_huge_page_test result check" from Zi Yan improves our
folio splitting selftest code
- "test that rmap behaves as expected" from Wei Yang adds some rmap
selftests
- "remove write_cache_pages()" from Christoph Hellwig removes that
function and converts its two remaining callers
- "selftests/mm: uffd-stress fixes" from Dev Jain fixes some UFFD
selftests issues
- "introduce kernel file mapped folios |
